US20230217641A1 - Semiconductor memory structure - Google Patents
Semiconductor memory structure Download PDFInfo
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- US20230217641A1 US20230217641A1 US17/891,925 US202217891925A US2023217641A1 US 20230217641 A1 US20230217641 A1 US 20230217641A1 US 202217891925 A US202217891925 A US 202217891925A US 2023217641 A1 US2023217641 A1 US 2023217641A1
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/30—DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells
- H10B12/34—DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells the transistor being at least partially in a trench in the substrate
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
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- H01L27/108—
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C5/00—Details of stores covered by group G11C11/00
- G11C5/06—Arrangements for interconnecting storage elements electrically, e.g. by wiring
- G11C5/063—Voltage and signal distribution in integrated semi-conductor memory access lines, e.g. word-line, bit-line, cross-over resistance, propagation delay
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/01—Manufacture or treatment
- H10B12/02—Manufacture or treatment for one transistor one-capacitor [1T-1C] memory cells
- H10B12/03—Making the capacitor or connections thereto
- H10B12/033—Making the capacitor or connections thereto the capacitor extending over the transistor
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/01—Manufacture or treatment
- H10B12/02—Manufacture or treatment for one transistor one-capacitor [1T-1C] memory cells
- H10B12/03—Making the capacitor or connections thereto
- H10B12/033—Making the capacitor or connections thereto the capacitor extending over the transistor
- H10B12/0335—Making a connection between the transistor and the capacitor, e.g. plug
Definitions
- FIGS. 2 - 14 illustrate cross-sectional views of forming semiconductor memory structure at different stages, wherein the extending portion of the semiconductor material is completely silicided, according to some embodiments of the present disclosure.
- the first nitride liner 131 and the oxide liner 132 are deposited by a deposition process, and then the etch back process is used to remove the first nitride liner 131 and the oxide liner 132 on the top surface of the bit line 120 and on the top surface of the cap layer 110 . Finally, the nitride liner 133 is deposited by the deposition process, so that the oxide liner 132 is sandwiched between the first nitride liner 131 and the second nitride liner 133 .
- a nitride material layer 143 is conformally deposited by the deposition process. Then, the nitride material layer 143 on the top surface of the semiconductor material 141 and on the top surface of the bit line 120 is etched by an etching process until a portion of the top surface of the semiconductor material 141 is exposed, and leaving the nitride layer 144 on both sides of the bit line 120 .
- the body portion 141 b and the extending portion 141 t only intersect at one point. That is, the top surface of the body portion 141 b is substantially level with the bottom surface of the extending portion 141 t .
- the body portion 141 b and the extending portion 141 t are connected to each other by a portion of their sidewalls. In still other embodiments, the body portion 141 b and the extending portion 141 are not connected to each other.
- an adhesive layer material is formed along the surface of the metal silicide liner 146 by a deposition process and a planarization process.
- a metal material is then formed on the adhesive layer material. The excess portion is removed by a planarization process to form the adhesive layer 147 and the metal plug 148 .
- a dielectric layer 152 , a conductive barrier layer 154 and a capacitor structure 160 are formed on the capacitor contact 140 and the bit line 120 .
- the semiconductor plug 141 b ′ further includes the extension portion 141 t ′, which may further reduce the capacitance value of the bit line.
- FIGS. 17 - 18 are cross-sectional views of forming a semiconductor memory structure at different stages according to other embodiments of the present disclosure.
- FIGS. 19 - 20 are cross-sectional views of forming a semiconductor memory structure at different stages according to some other embodiments of the present disclosure.
- the embodiments of the present disclosure may reduce the resistance of the capacitor contacts and improve the uniformity of the metal silicide liner by disposing the sidewall portion of the metal silicide liner on both sides of the metal plug.
- the capacitance value of the bit line may be further reduced by disposing the extending portion of the semiconductor plug on the sidewall portion of the metal silicide liner.
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- Engineering & Computer Science (AREA)
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- Internal Circuitry In Semiconductor Integrated Circuit Devices (AREA)
- Semiconductor Memories (AREA)
- Metal-Oxide And Bipolar Metal-Oxide Semiconductor Integrated Circuits (AREA)
Abstract
A semiconductor memory structure includes a semiconductor substrate, a bit line disposed on the semiconductor substrate, a dielectric liner disposed on a sidewall of the bit line and a capacitor contact disposed on a side of the bit line. The dielectric liner includes a first nitride liner disposed on a sidewall of the bit line, an oxide liner disposed on a sidewall of the first nitride liner, and a second nitride liner disposed on a sidewall of the oxide liner. The capacitor contact includes a semiconductor plug disposed on the semiconductor substrate, a metal plug disposed on the semiconductor plug, a metal silicide liner including a sidewall portion and a bottom portion extending along the sidewall and the bottom of the metal plug respectively, and a nitride layer disposed on the metal silicide liner. The sidewall portion is disposed directly above the second nitride liner.
Description
- This application claims priority of Taiwan Patent Application No. 111100159, filed on Jan. 4, 2022, the entirety of which is incorporated by reference herein.
- The present disclosure relates to a semiconductor memory structure, and in particular it relates to a contact structure of dynamic random access memory.
- Dynamic random access memory (DRAM) is widely used in consumer electronic products. In order to increase the device density in the DRAM device and improve the performance of these devices, current DRAM manufacturing technology continues to trend towards miniaturization of the devices.
- However, as the dimensions of the device continue to shrink, many challenges arise. For example, in the semiconductor manufacturing process, there is a small contact area between the semiconductor plug and the metal plug, and so a large capacitance value is generated between the bit lines. In addition, when the polysilicon is annealed, since the surrounding materials are not the same, the stress and the growth temperature are not the same. Thus, the silicide layer is prone to non-uniformity at the corners. Therefore, the industry still needs to improve the technology used to process dynamic random access memory to overcome the problems caused by shrinking device sizes.
- In accordance with some embodiments of the present disclosure, a semiconductor memory structure is provided. The semiconductor memory structure includes a semiconductor substrate, a bit line disposed on the semiconductor substrate, a dielectric liner disposed on a sidewall of the bit line and a capacitor contact disposed on a side of the bit line. The dielectric liner includes a first nitride liner disposed on a sidewall of the bit line, an oxide liner disposed on a sidewall of the first nitride liner, and a second nitride liner disposed on a sidewall of the oxide liner. The capacitor contact includes a semiconductor plug disposed on the semiconductor substrate, a metal plug disposed on the semiconductor plug, a metal silicide liner including a sidewall portion and a bottom portion that respectively extend along a sidewall and a bottom of the metal plug, and a nitride layer disposed on the metal silicide liner. The sidewall portion is disposed directly above the second nitride liner.
- To make the features and advantages of the present invention more obvious and understandable, different embodiments are specially cited below, and detailed descriptions are as follows in conjunction with the accompanying drawings:
-
FIG. 1 illustrates a top view of semiconductor memory structure according to some embodiments of the present disclosure. -
FIGS. 2-14 illustrate cross-sectional views of forming semiconductor memory structure at different stages, wherein the extending portion of the semiconductor material is completely silicided, according to some embodiments of the present disclosure. -
FIGS. 15-16 illustrate cross-sectional views of semiconductor memory structure at different stages, wherein the extending portion of the semiconductor material is not completely silicided, according to other embodiments of the present disclosure. -
FIGS. 17-18 illustrate cross-sectional views of forming semiconductor memory structure at different stages, wherein in the height direction, the bottom surface of the sidewall portion of the metal silicide layer is lower than the top surface of the bottom portion of the metal silicide liner, according to some other embodiments of the present disclosure. -
FIGS. 19-20 illustrate cross-sectional views of forming semiconductor memory structure at different stages, wherein in the height direction, the bottom surface of the sidewall portion of the metal silicide layer is higher than the top surface of the bottom portion of the metal silicide liner, according to further some other embodiments of the present disclosure. -
FIG. 1 illustrates a top view of semiconductor memory structure according to some embodiments of the present disclosure. In some embodiments, thesemiconductor memory structure 100 is a portion of a dynamic random access memory (DRAM) array. In some embodiments,semiconductor memory structure 100 includes asemiconductor substrate 102,word lines 106,bit line contacts 108,bit lines 120,dielectric liners 130, andcapacitor contacts 140. - The
semiconductor substrate 102 includes anactive region 102A and anisolation region 102B surrounding theactive region 102A. Thedielectric liner 130 includes a pair ofnitride liners oxide liner 132 sandwiched between the pair ofnitride liners capacitor contact 140 includes ametal plug 148 and anadhesive layer 147 and anitride layer 144 surrounding themetal plug 148. - In this top view embodiment, the
word line 106 extends along a first direction D1, thebit line 120 extends along a second direction D2, and theactive region 102A extends along a third direction D3. In this embodiment, the first direction D1 is perpendicular to the second direction D2, and the third direction D3 (that is, the extending direction of theactive region 102A) and the second direction D2 present an angle of about 10-40°, such as 20°, in order to improve the integration of elements. - In this top-view embodiment, the
capacitor contact 140 extends through thesecond nitride liner 133 andoxide liner 132 but not penetrates throughfirst nitride liner 131 in a first direction D1. In this embodiment, thenitride layer 144 is in direct contact with thefirst nitride liner 131, theoxide liner 132, and thesecond nitride liner 133. - It should be noted that
FIG. 1 only shows some elements of a dynamic random access memory (DRAM) to simplify the figures. Subsequent figures are cross-sectional views (a plane formed by the first direction D1 and the height direction Z) along the cross sectional line A-A′ inFIG. 1 to facilitate the description of the method of forming the semiconductor memory structure. -
FIGS. 2-14 illustrate cross-sectional views of forming semiconductor memory structure at different stages, according to some embodiments of the present disclosure. - As shown in
FIG. 2 , asemiconductor substrate 102 is provided. Thesemiconductor substrate 102 includes anactive region 102A and anisolation region 102B, which are arranged in a staggered manner. InFIG. 2 , anisolation member 104 is disposed in theisolation region 102B of thesemiconductor substrate 102, and theisolation member 104 includes anisolation liner 1041 and anisolation filler 1042. - In some embodiments, the word lines (not shown) are buried in the active region of the semiconductor substrate. In some embodiments, the word line acts as a gate and includes a gate dielectric layer, a gate liner, and a gate electrode (not shown). It should be noted that since the
word line 106 inFIG. 1 extends along the first direction D1, and the cross sectional line A-A′ does not touch theword line 106, the word line is not shown inFIG. 2 . - In
FIG. 2 , thebit line contact 108 is partially embedded in theactive region 102A of thesemiconductor substrate 102 to facilitate subsequent electrical connection with thebit line 120. In some embodiments,spacers 109 are disposed on both sides of thebit line contact 108 to prevent the bit line contact from being short-circuited by connecting the subsequently formed capacitor contact. - In some embodiments, the
bit line contact 108 is doped polysilicon to reduce contact resistance with subsequently formed bit lines. Dopants may include n-type or p-type dopants such as nitrogen, arsenic, phosphorus, antimony ions or boron, aluminum, gallium, indium, boron trifluoride ions (BF3+). - In some embodiments, the
spacer 109 is a dielectric material including a nitride, such as silicon nitride. - Please continue to refer to
FIG. 2 , acap layer 110 is formed on thesemiconductor substrate 102 to protect the elements in the semiconductor substrate from being damaged by subsequent processes. In some embodiments, thecap layer 110 includes anoxide layer 112 and anitride layer 114. - In some embodiments, the
oxide layer 112 includes a silicon oxide layer formed of tetraethylorthosilicate (TEOS). In some embodiments, thenitride layer 114 includes silicon nitride (SiN) or silicon oxynitride (SiON). In some embodiments, theoxide layer 112 and thenitride layer 114 may be sequentially formed by the deposition processes as described above. - Next, as shown in
FIG. 2 , the step of forming thebit line 120 on thesemiconductor substrate 102 also includes forming thebit line 120 on thebit line contact 108. In some embodiments, thebit line 120 on thebit line contact 108 includesconductive layers bit line contact 108, anddielectric layers conductive layers bit line 120 on theisolation member 104 includes adielectric layer 121 on thecap layer 110,conductive layers dielectric layer 121, anddielectric layers conductive layers dielectric layers 144 and 145, the underlying layers (such as theconductive layers 122 and 123) may be protected from being damaged in the subsequent processes. - In some embodiments, the
conductive layers dielectric layers - Next, as shown in
FIG. 2 , adielectric liner 130 is formed on the two sidewalls and the top surface of thebit line 120 and on thecap layer 110, which may prevent thebit line 120 from being short-circuited by directly contacting the subsequently formed capacitor contacts. - In some embodiments, the
dielectric liner 130 disposed on the two sidewalls of thebit line 120 includes afirst nitride liner 131 and asecond nitride liner 133, and an oxide liner disposed therebetween. Theoxide liner 132 is used to prevent parasitic capacitances from being generated between thebit lines 120 and the capacitor contacts that are formed subsequently. In an alternative embodiment, theoxide liner 132 may also be replaced by an air gap. - In some embodiments, the
dielectric liner 130 on the top surface of thebit line 120 and on thecap layer 110 only includes thesecond nitride liner 133 to protect the underlying film from being affected by the subsequent processes. - In some embodiments, the
first nitride liner 131 and theoxide liner 132 are deposited by a deposition process, and then the etch back process is used to remove thefirst nitride liner 131 and theoxide liner 132 on the top surface of thebit line 120 and on the top surface of thecap layer 110. Finally, thenitride liner 133 is deposited by the deposition process, so that theoxide liner 132 is sandwiched between thefirst nitride liner 131 and thesecond nitride liner 133. - Next,
FIGS. 3-13 are cross-sectional views of forming thecapacitor contact 140 on a side of thebit line 120 at different stages. - As shown in
FIG. 3 , thecap layer 110 and thesemiconductor substrate 102 are etched (including etching a portion of the spacer 109) along the sidewall of thedielectric liner 120 by an etch-back process, so that the subsequently formed capacitors are electrically connected with theactive region 102A of thesemiconductor substrate 102. - Next, as shown in
FIGS. 4-5 , asemiconductor material 141 is deposited by a deposition process, and then thesemiconductor material 141 is etched by an etch-back process. By doing so, the top surface of thesemiconductor material 141 is lower than the top surface of thedielectric layer 125 of thebit line 120, and higher than theconductive layer 123 of thebit line 120. In some embodiments, thesemiconductor material 141 includes doped polysilicon. - Next, as shown in
FIG. 6 , thesecond nitride liner 133 and theoxide liner 132 on thesemiconductor material 141 are removed by an etching process. In this embodiment, the etchant comprises SiCoNi to etch thesecond nitride liner 133 andoxide liner 132 without substantially etching thesemiconductor material 141. In addition, thefirst nitride liner 131 may be used as an etch stop layer, and the etching process can be stopped by an etching signal. In this way, thefirst nitride liner 131 may be retained on the sidewalls of theentire bit line 120 and protect thebit line 120 from being affected by the subsequent processes. Here, the removal of thesecond nitride liner 133 and theoxide liner 132 may include removing a portion of the uppermostdielectric layer 125 of thebit line 120. That is, the height of thebit line 120 may be slightly decreased due to the etching process. In other embodiments, the removal of thesecond nitride liner 133 and theoxide liner 132 does not include removing a portion of thebit line 120. That is, the height of thebit line 120 may not be affected by the etching process. - Next, as shown in
FIGS. 7-8 , thesemiconductor material 141 is re-deposited by the deposition process, and thesemiconductor material 141 is etched by the etch-back process again. By doing so, the top surface of thesemiconductor material 141 is lower than the top surface of thedielectric layer 125 of thebit line 120 and is higher than the top surfaces of theoxide liner 132 and thesecond nitride liner 133. - Next, as shown in
FIGS. 9-10 , anitride material layer 143 is conformally deposited by the deposition process. Then, thenitride material layer 143 on the top surface of thesemiconductor material 141 and on the top surface of thebit line 120 is etched by an etching process until a portion of the top surface of thesemiconductor material 141 is exposed, and leaving thenitride layer 144 on both sides of thebit line 120. - In some embodiments, the top surface of the
nitride layer 144 is level with the top surfaces of thefirst nitride liner 131 and thebit line 120, so that thenitride layer 144 has a finer pattern, which is benefit for subsequent definition of the metal silicide liner. In addition, the sidewalls of thenitride layer 144 directly contact the sidewalls of thefirst nitride liner 131. - By replacing the
upper oxide liner 132 with thenitride layer 144 and thesemiconductor material 141, subsequent damage to the oxide liner due to a post-clean process may be prevented. - Next, as shown in
FIG. 11 , using thenitride layer 144 as an etch mask, thesemiconductor material 141 is etched by the etching process to form arecess 1410 in thesemiconductor material 141. Thesemiconductor material 141 is divided into the extendingportion 141 t on the sidewall of therecess 1410 and thebody portion 141 b under the bottom of therecess 1410. In some embodiments, the top surface of thebody portion 141 b is lower than the top surface of the extendingportion 141 t and is higher than the top surface of theconductive layer 123 of thebit line 120. In some embodiments, at least a portion of thebody portion 141 b and at least a portion of the extendingportion 141 t will be converted into a metal silicide liner subsequently. - In
FIG. 11 , thebody portion 141 b and the extendingportion 141 t only intersect at one point. That is, the top surface of thebody portion 141 b is substantially level with the bottom surface of the extendingportion 141 t. In other embodiments, thebody portion 141 b and the extendingportion 141 t are connected to each other by a portion of their sidewalls. In still other embodiments, thebody portion 141 b and the extendingportion 141 are not connected to each other. - Next, as shown in
FIG. 12 , a portion of thesemiconductor material 141 is converted into ametal silicide liner 146 by a silicidation process to reduce the contact resistance with subsequent metal plugs (not shown). Specifically, the extendingportion 141 t extending along the side surface of therecess 1410 is completely converted into thesidewall portion 146 s of themetal silicide liner 146, and thebody portion 141 b extending along the bottom of therecess 1410 is partially converted into thebottom portion 146 b of themetal silicide liner 146. Here, the remainingsemiconductor material 141 is referred to as asemiconductor plug 141, and the remainingbody portion 141 b is referred to as abody portion 141 b′. - In some embodiments, due to the silicidation process, the
bottom portion 146 b presents curve at the corner C, so thesidewall portion 146 s is not in direct contact with thebottom portion 146 b. In some embodiments, in the height direction Z, the bottom surface of thesidewall portion 146 s is level with the top surface of thebottom portion 146 b. It should be noted that here, the top surface of thebottom portion 146 b is represented as the top surface of the highest point of thebottom portion 146 b. - In some embodiments, in the height direction Z, the
sidewall portion 146 s is sandwiched between thenitride layer 144 and thesecond nitride liner 133. In some embodiments, in the height direction Z, the sidewall of thenitride layer 144, the sidewall of thesidewall portion 146 s, and the sidewall of thesecond nitride liner 133 are aligned with each other. That is, in the height direction Z, thenitride layer 144, thesidewall portion 146 s and thesecond nitride liner 133 are arranged from top to bottom. That is, thesidewall portion 146 s is located directly above thesecond nitride liner 133. In some embodiments, thesidewall portion 146 s is disposed on the sidewall of thefirst nitride liner 131, and thebottom portion 146 b is disposed on the sidewall of thesecond nitride liner 133. - In
FIG. 12 , in the height direction Z, thesidewall portion 146 s is disposed directly above theoxide liner 132. That is, the bottom surface of thesidewall portion 146 s directly contact the top surface of theoxide liner 132 and the top surface of thesecond nitride liner 133. InFIG. 12 , in the height direction Z, the sidewall of thenitride layer 144, the sidewall of thesidewall portion 146 s, and the sidewall of theoxide liner 132 are aligned with each other. - In some embodiments, the silicidation process includes first depositing a metal (such as cobalt) on the
semiconductor material 141 including the extendingportion 141 t and thebody portion 141 b. The silicidation process further includes performing an annealing process to the metal, and then using a wet etching process to remove the unreacted portion of the metal to form ametal silicide liner 146. In some embodiments, themetal silicide liner 146 includes cobalt silicon (CoSi). - Compared with the semiconductor material only having the body portion, in the embodiment of the present disclosure, the semiconductor material further includes the extending portion, so that the semiconductor material at the corners may have more uniform stress and growth temperature during the silicidation process since contacting the similar material, thereby improving the uniformity of the metal silicide layer. That is, the
bottom portion 146 b of themetal silicide layer 146 in the embodiment of the present disclosure does not drop significantly at the corner C (thebottom portion 146 b only forms a relatively flat arc surface at the corner C), and the uniformity of thebottom portion 146 b may be improved. - In the embodiment of the present disclosure, the sidewall portion of the metal silicide liner may increase the contact area with the subsequently formed metal plug, so as to further reduce the contact resistance.
- In some embodiments, since the extending
portion 141 t and thebody portion 141 b of thesemiconductor material 141 are simultaneously converted into thesidewall portion 146 s and thebottom portion 146 b of themetal silicide liner 146 through the silicidation process, the width W146 s of thesidewall portion 146 s is substantially equal to the thickness T146 of thebottom portion 146 b. - In some embodiments, the width W146 s of the
sidewall portion 146 s of themetal silicide liner 146 is not greater than the sum (W132+W133) of the width W132 of theoxide liner 132 and the width W133 of thesecond nitride liner 133. InFIG. 12 , the width W146 s of thesidewall portion 146 s of themetal silicide liner 146 is equal to the width W132 of theoxide liner 132 and the width W133 of thesecond nitride liner 133. In this way, the width of the metal plug to be formed subsequently may be maintained, and the offset between the subsequent metal plug and the conductive barrier layer may be prevented. - In some embodiments, the ratio of the width W146 sof the
sidewall portion 146 s of themetal silicide liner 146 and the width W120 of thebit line 120 is between 1%-65%. As being between the above ratio, the contact resistance of the capacitor contact may be reduced without offsetting the subsequent metal plug and the conductive barrier layer. InFIG. 12 , the ratio is between 40%-65%. - Next, as shown in
FIG. 13 , an adhesive layer material is formed along the surface of themetal silicide liner 146 by a deposition process and a planarization process. A metal material is then formed on the adhesive layer material. The excess portion is removed by a planarization process to form theadhesive layer 147 and themetal plug 148. - In
FIG. 13 , thecapacitor contact 140 includes a semiconductor plug (only thebody portion 141 b′ inFIG. 13 ) disposed on thesemiconductor substrate 102. The semiconductor plug includes ametal silicide liner 146, anitride layer 144, and anadhesive layer 147. Themetal silicide liner 146 includes thesidewall portion 146 s and thebottom portion 146 b extending along the sidewalls and the bottom of themetal plug 148 respectively. Thenitride layer 144 is disposed on themetal silicide liner 146. Theadhesive layer 147 is disposed between themetal silicide liner 146 and themetal plug 148. - In some embodiments, the
adhesive layer 147 may increase the adhesion between themetal silicide liner 146 and themetal plug 148. In some embodiments, the top surface of theadhesive layer 147, the top surface of themetal plug 148 and the top surface of thenitride layer 144 are level. In some embodiments, since theadhesive layer 147 is formed along thesidewall portion 146 s and thebottom portion 146 b of themetal silicide liner 146, theadhesive layer 147 generally presents a U-shape and surrounds themetal plug 148. - In some embodiments, the
adhesive layer 147 extends along the sidewall of thenitride layer 144 andsidewalls 146 s and bottom 146 b of themetal silicide liner 146. Theadhesive layer 147 is in direct contact with thenitride layer 144 and thesidewall portion 146 s and thebottom portion 146 b of themetal silicide liner 146. In some embodiments, theadhesive layer 147 includes titanium (Ti) or titanium nitride (TiN) or the like. - In some embodiments, the top surface of the
metal plug 148 is level with the top surface of thenitride layer 144. In some embodiments, in the height direction Z, the top surface of thesidewall portion 146 s of themetal silicide liner 146 is lower than the top surface of themetal plug 148. In some embodiments, thesidewall portion 146 s of themetal silicide liner 146 and thenitride layer 144 are both disposed between thefirst nitride liner 131 and themetal plug 148. - In some embodiments, the sidewalls of the upper portion of the
metal plug 148 are surrounded by thenitride layer 144, and the sidewalls of the lower portion of themetal plug 148 are surrounded by thesidewall portions 146 s of themetal silicide liner 146. - Compared with the case where the metal silicide liner is only disposed on the bottom of the metal plug, in the embodiment of the present disclosure, the
metal silicide liner 146 is further disposed on the sidewall of themetal plug 148 to increase the contact area, thereby reducing the resistance of the capacitor contact. - In some embodiments, the bottom surface of the
metal plug 148 is not lower than the top surface of theconductive layer 123 of thebit line 120, thereby reducing the capacitance value of thebit line 120 and thecapacitor contact 140. - In some embodiments, the
semiconductor substrate 102 under thebit line contact 108 has a doped region (not shown), which can serve as a source, and thesemiconductor substrate 102 under thecapacitor contact 140 also has a doped region (not shown), which can act as a drain. As shown inFIG. 1 , in anyactive region 102A extending along the third direction D3, the arrangement sequence is thecapacitor contact 140, theword line 106, thebit line contact 108, theword line 106, thecapacitor contact 140, and may act as a drain, a gate, a source, a gate, and a drain, respectively. That is, theactive region 102A includes two groups of transistor structures sharing the same source electrode, so that the layout may be much effectively utilized to save the manufacturing cost. - Next, referring to
FIG. 14 , adielectric layer 152, aconductive barrier layer 154 and acapacitor structure 160 are formed on thecapacitor contact 140 and thebit line 120. - In some embodiments, in the first direction D1, the
dielectric layer 152 and theconductive barrier layer 154 are arranged alternately. Theconductive barrier layer 154 is directly above thecapacitor contact 140 and spans over to thenitride layer 144. In some embodiments, theconductive barrier layer 154 includes a material, such as tungsten or copper, which may block the penetration of an etching solution. - In some embodiments, the
capacitor structure 160 includes electrode layers 162 and 166 and adielectric layer 164 sandwiched therebetween. In some embodiments, theelectrode layer 162 is formed on theconductive barrier layer 154 and has a U-shaped cross-sectional profile. In some embodiments, thedielectric layer 164 extends along theelectrode layer 162 and theconductive barrier layer 154 and is a continuous film. It should be noted that thecapacitor structure 160 inFIG. 14 is only an example, and those with ordinary skill in the art may also apply capacitor structures different from those shown inFIG. 14 on thecapacitor contact 140. - In some embodiments, the
dielectric layer 164 may include silicon nitride (Si3N4), aluminum oxide (Al2O3), yttrium oxide (Y2O3), titanium oxide (TiO), hafnium dioxide (HfO2), or zirconium dioxide (ZrO2) and so on. In some embodiments, the electrode layers 162 and 166 may include silicon germanium (SiGe), titanium, titanium nitride, tungsten nitride, tantalum or tantalum nitride and so on in order to reduce leakage current. - It should be noted that, after the
capacitor structure 160 is formed, additional components, such as metal layers and dielectric layers, may still be formed to complete the fabrication of memory devices such as dynamic random access memory (DRAM). - In summary, in the embodiments of the present disclosure, by forming the sidewalls and the bottom of the metal silicide liner, the uniformity of the metal silicide liner may be improved, and the resistance in the capacitor contacts may also be reduced, thereby improving the semiconductor performance.
-
FIGS. 15-16 are cross-sectional views of forming a semiconductor memory structure at different stages according to other embodiments of the present disclosure. - Following
FIG. 11 , as shown inFIG. 15 , a portion of the extendingportion 141 t extending along the sidewall of therecess 1410 is converted into thesidewall portion 146 s of themetal silicide liner 146 by a silicidation process. The portion of thebody portion 141 b extending along the bottom of therecess 1410 is converted into thebottom portion 146 b of themetal silicide liner 146. Here, the remainingsemiconductor material 141 is referred to as asemiconductor plug 141, the remainingbody portion 141 b is referred to as abody portion 141 b′, and the remaining extendingportion 141 t is referred to as an extendingportion 141 t′. In some embodiments, thebody portion 141 b′ is not in contact with the extendingportion 141 t′. - In
FIG. 15 , in the height direction Z, the extendingportion 141 t′ is disposed directly above theoxide liner 132. That is, the bottom surface of the extendingportion 141 t′ is in direct contact with the top surface of theoxide liner 132. - In
FIG. 15 , in the height direction Z, the sidewall of thenitride layer 144, the sidewall of the extendingportion 141 t′, and the sidewall of theoxide liner 132 are aligned with each other. That is, in the height direction Z, thenitride layer 144, the extendingportion 141 t′ and theoxide liner 132 are arranged in sequence from top to bottom. In other words, in the height direction Z, the extendingportion 141 t′ is sandwiched between thenitride layer 144 and theoxide liner 132. - In
FIG. 15 , the extendingportion 141 t′ is disposed on the sidewall of thefirst nitride liner 131, and thebody portion 141 b′ is disposed on the sidewall of thesecond nitride liner 133. In the first direction D1, the extendingportion 141 t′ is disposed between thefirst nitride liner 131 and thesidewall portion 146 s of themetal silicide liner 146. - In
FIG. 15 , the width W146 s of thesidewall portion 146 s of themetal silicide liner 146 is less than the sum of the width W132 of theoxide liner 132 and the width W133 of thesecond nitride liner 133. The width W146 s of thesidewall portion 146 s of themetal silicide liner 146 is substantially equal to the thickness T146 b of thebottom portion 146 b. InFIG. 15 , the ratio of the width W146 s of thesidewall portion 146 s of themetal silicide liner 146 and the width W120 of thebit line 120 is between 1%-40% or 5%-30%. - In the embodiment of the present disclosure, the
semiconductor plug 141 b′ further includes theextension portion 141 t′, which may further reduce the capacitance value of the bit line. - Next, similar to the above-mentioned process, the
adhesive layer 147 and themetal plug 148 are formed, and the semiconductor memory structure as shown inFIG. 16 may be obtained. -
FIGS. 17-18 are cross-sectional views of forming a semiconductor memory structure at different stages according to other embodiments of the present disclosure. - Continuing from
FIG. 10 , as shown inFIG. 17 , arecess 1410 is formed in thesemiconductor material 141, and thesemiconductor material 141 is divided into an extendingportion 141 t on the sidewall of therecess 1410 and abody portion 141 b under the bottom of the recess. Thebody portion 141 b and a portion of the sidewall of the extendingportion 141 t are connected to each other by a portion of their sidewalls. The semiconductor memory structure as shown inFIG. 18 may be obtained by a process similar to the above-mentioned process. -
FIG. 18 is similar toFIG. 13 . The difference betweenFIG. 18 andFIG. 13 is that in the height direction Z, the bottom surface of thesidewall portion 146 s of themetal silicide liner 146 is lower than the top surface of thebottom portion 146 b. In this way, the bottom 146 b of themetal silicide liner 146 may reduce more effectively different stress and growth temperature at the corners due to different materials, thereby further improving the uniformity. -
FIGS. 19-20 are cross-sectional views of forming a semiconductor memory structure at different stages according to some other embodiments of the present disclosure. - Following
FIG. 10 , as shown inFIG. 19 , arecess 1410 is formed in thesemiconductor material 141, and thesemiconductor material 141 is divided into an extendingportion 141 t on the sidewall of therecess 1410 and abottom portion 141 b under the bottom of the recess. Thebody portion 141 b is not connected to the sidewall of the extendingportion 141 t (or when thebody portion 141 b and the extendingportion 141 t are projected to the height direction Z, they do not contact each other). The semiconductor memory structure shown inFIG. 20 may be obtained by a process similar to the above-mentioned process. -
FIG. 20 is similar toFIG. 18 . The difference betweenFIG. 20 andFIG. 18 is that in the height direction Z, the bottom surface of thesidewall portion 146 s of themetal silicide liner 146 is higher than the top surface of thebottom portion 146 b. In this way, the contact area of the metal plug may be increased, thereby reducing the resistance in the capacitor contact. - In summary, the embodiments of the present disclosure may reduce the resistance of the capacitor contacts and improve the uniformity of the metal silicide liner by disposing the sidewall portion of the metal silicide liner on both sides of the metal plug. In addition, the capacitance value of the bit line may be further reduced by disposing the extending portion of the semiconductor plug on the sidewall portion of the metal silicide liner.
- Although the present invention is disclosed in the foregoing embodiments, it is not intended to limit the present invention. Those with ordinary skill in the technical field to which the present invention pertains can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be subject to those defined by the scope of the appended claims.
Claims (20)
1. A semiconductor memory structure, comprising:
a semiconductor substrate;
a bit line disposed on the semiconductor substrate;
a dielectric liner disposed on a sidewall of the bit line, wherein the dielectric liner comprises:
a first nitride liner disposed on a sidewall of the bit line;
an oxide liner disposed on a sidewall of the first nitride liner; and
a second nitride liner disposed on a sidewall of the oxide liner; and
a capacitor contact disposed on a side of the bit line, wherein the capacitor contact comprises:
a semiconductor plug disposed on the semiconductor substrate;
a metal plug disposed on the semiconductor plug;
a metal silicide liner comprising a sidewall portion and a bottom portion respectively extending along a sidewall and a bottom of the metal plug, wherein the sidewall portion is disposed directly above the second nitride liner; and
a nitride layer disposed on the metal silicide liner.
2. The semiconductor memory structure as claimed in claim 1 , wherein the sidewall portion is not in direct contact with the bottom portion.
3. The semiconductor memory structure as claimed in claim 1 , wherein the sidewall portion is disposed between the first nitride liner and the metal plug.
4. The semiconductor memory structure as claimed in claim 1 , wherein in a height direction, the sidewall portion is sandwiched between the nitride layer and the second nitride liner.
5. The semiconductor memory structure as claimed in claim 1 , wherein the sidewall portion is disposed on the sidewall of the first nitride liner and the bottom portion is disposed on a sidewall of the second nitride liner.
6. The semiconductor memory structure as claimed in claim 1 , wherein the nitride layer is disposed between the first nitride liner and the metal plug.
7. The semiconductor memory structure as claimed in claim 1 , wherein a sidewall of the nitride layer, a sidewall of the sidewall portion and a sidewall of the second nitride liner are aligned with each other.
8. The semiconductor memory structure as claimed in claim 1 , wherein the sidewall portion is in direct contact with the oxide liner.
9. The semiconductor memory structure as claimed in claim 1 , wherein the semiconductor plug comprises a body portion disposed under the bottom portion and an extending portion disposed on a sidewall of the sidewall portion, wherein the body portion is not in contact with the extending portion.
10. The semiconductor memory structure as claimed in claim 9 , wherein the extending portion is disposed directly above the oxide liner.
11. The semiconductor memory structure as claimed in claim 9 , wherein in a height direction, the extending portion is sandwiched between the nitride layer and the oxide liner.
12. The semiconductor memory structure as claimed in claim 9 , wherein the extending portion is disposed on a sidewall of the first nitride liner, and the body portion is disposed on a sidewall of the second nitride liner.
13. The semiconductor memory structure as claimed in claim 9 , wherein the extending portion is disposed between the first nitride liner and the sidewall portion.
14. The semiconductor memory structure as claimed in claim 1 , wherein in a top view, the nitride layer is in direct contact with the first nitride liner, the oxide liner, and the second nitride liner.
15. The semiconductor memory structure as claimed in claim 1 , wherein a width of the sidewall portion is substantially equal to a thickness of the bottom portion.
16. The semiconductor memory structure as claimed in claim 1 , wherein a width of the sidewall portion is less than or equal to a sum of a width of the oxide liner and a width of the second nitride liner.
17. The semiconductor memory structure as claimed in claim 1 , wherein a ratio of a width of the sidewall portion and a width of the bit line is 1%-65%.
18. The semiconductor memory structure as claimed in claim 1 , wherein the nitride layer surrounds an upper portion of the metal plug and the sidewall portion surrounds a lower portion of the metal plug.
19. The semiconductor memory structure as claimed in claim 1 , wherein the bit line comprises a conductive layer, wherein a top surface of the conductive layer is not higher than a bottom surface of the metal plug.
20. The semiconductor memory structure as claimed in claim 1 , wherein the capacitor contact further comprises an adhesive layer disposed between the metal silicide liner and the metal plug.
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TW111100159A TWI806330B (en) | 2022-01-04 | 2022-01-04 | Semiconductor memory structure |
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US20230180463A1 (en) * | 2021-04-15 | 2023-06-08 | Changxin Memory Technologies, Inc. | Methods for manufacturing semiconductor devices, and semiconductor devices |
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